Syringe and apparatus for manufacturing the same

Abstract

The present invention provides a syringe including a tubular barrel. The tubular barrel has an open proximal end, a distal end with a fluid expelling passage defined therein, and a barrel chamber. A seal is disposed within the barrel chamber a predetermined distance away from the open proximal end in fluid-tight and axially-sliding engagement with the barrel chamber, so that fluid held in the barrel chamber between the fluid expelling passage and the seal can be expelled from the barrel chamber to the outside via the fluid expelling passage by sliding the seal towards the fluid expelling passage. The seal defines at least two diametrically enlarged portions at axially spaced apart portions of the seal so as to be respectively in abutment with the inner wall of the barrel chamber and a concave portion between adjacent diametrically enlarged portions of the at least two diametrically enlarged portions for defining a clearance relative to the inner wall of the barrel chamber, in which lubricant film exists at interfaces between the at least two diametrically enlarged portions of the seal and the inner wall of the barrel chamber, and lubricant is filled in the clearance. The present invention also provides a syringe assembly and an apparatus for manufacturing the syringe having the above arrangement.

What is claimed is: 
     
       1. A syringe comprising: a tubular barrel having an open proximal end, a distal end with a fluid expelling passage defined therein, and a barrel chamber;   a seal being disposed within said barrel chamber a predetermined distance away from said open proximal end in fluid-tight and axially-sliding engagement with said barrel chamber, so that fluid held in said barrel chamber between said fluid expelling passage and said seal can be expelled from said barrel chamber to the outside via said fluid expelling passage by sliding said seal towards said fluid expelling passage; and   said seal defining at least two diametrically enlarged portions at axially spaced apart portions on said seal so as to be respectively in abutment with the inner wall of said barrel chamber and a concave portion between adjacent diametrically enlarged portions of said at least two diametrically enlarged portions for defining a clearance relative to said inner wall of said barrel chamber;   wherein lubricant film exists at interfaces between said at least two diametrically enlarged portions of said seal and said inner wall of said barrel chamber, and lubricant is filled in said clearance.   
     
     
       2. The syringe as set forth in claim 1, wherein said lubricant film does not exist at an interface between said inner wall of said barrel chamber and a diametrically enlarged portion that is distally positioned among said at least two diametrically enlarged portions. 
     
     
       3. A syringe assembly comprising the syringe of claim 1 and a plunger rod having a proximal end projecting proximally from said open proximal end of said barrel, and a distal end being interconnected to said seal. 
     
     
       4. The syringe assembly as set forth in claim 3, wherein said syringe assembly contains a medical fluid that is pre-filled in said barrel chamber between said fluid expelling passage of said barrel and said seal.